GPS-X Technical Reference

The state variables in the prefermenter model are as follows:
Suspended Growth Models 150
C is: insoluble substrate (not passing through a 0.45 mm filter) such as cellulose,
fats, insoluble proteins (mg COD/L).
C ss: soluble, high molecular weight substrate, such as soluble carbohydrates
(starch), and soluble proteins (globular) (mg COD/L).
C mo: monomer species such as glucose, long-chain fatty acids, amino acids
(mg COD/L).
S lf: volatile fatty acids (mg COD/L).
C e: hydrolytic enzymes which act as a catalyst to hydrolyse insoluble substrate,
soluble high-molecular-weight substrate and proteins (mg COD/L).
C xa: acidogenic bacteria which utilize monomers (C mo) as their substrate (mg
COD/L).
C xm: methanogenic bacteria, which utilize volatile fatty acids (VFAs) as their
substrate then transforming it into methane gas (mg COD/L).
C prot: organic nitrogen contained in particulate proteins which is converted into
ammonia nitrogen in the ammonification process as particulate proteins are
hydrolysed. It is also produced from the decay of bacteria cells (mg N/L).
S nh: ammonia nitrogen (mg N/L).
CH 4,g: methane gas.
Stoichiometric Parameters
The stoichiometric parameters to be specified in the influent section are used to calculate
the concentration of soluble, high molecular weight substrate (C is) from the influent
readily biodegradable substrate (ss) and the concentration of methanogenic biomass (C xm)
from the influent slowly biodegradable substrate (X s):
f ss: fraction of soluble high molecular weight substrate (C is) in the influent readily
biodegradable substrate (ss).
f xm: fraction of methanogenic biomass (C xm) in the influent slowly biodegradable
substrate (X s).
f m: conversion factor from COD to cubic meters for methane production
(m 3 CH 4/g COD).
GPS-X Technical Reference